Choke stove heat regulator valve



June 22, 1965 w Q Nm JR ETAL 3,190,274

CHOKE STOVE HEAT REGULATOR VALVE Filed March 21. 1962 2 Sheets-Sheet 1 June 22, 1965 Filed March 21, 1962 W. 0- MANNING, JR., ETAL CHOKE STOVE HEAT REGULATOR VALVE 2 Sheets-Sheet 2 ova/m C4 0550 W/ZZMM 0. MAM W6, JR.

W/ZZ/AM MCOZZO06H INVENTORJ' ATTORA/E'Y United States Patent Ofiice 3,196,274 Patented June 22, 1965 CHOKE STOVE HEAT REGULATOR VALVE William G. Manning, In, Livonia, and William E.

McCoilough, Detroit, Mich, assignors to Holley Carburetor Company, Warren, Mich, a corporation of Michigan Filed Mar. 21, 1962, Ser. No. 181,342 7 Claims. (Cl. 123-119) This invention relates generally to internal combustion engine carburetors having thermostatically controlled automatic choke systems, and more particularly to novel means for reducing the temperature of the heated air used to warm the thermostatic element prior to its entry into the choke housing.

Most carburetors currently include a bimetallic thermosatt spring for controlling the amount of choke opening according to temperature. In other words, when the engine is cold the bimetallic spring, through appropriate linkage, closes the choke plate for the starting operation. As the engine warms up, hot air is circulated through the choke housing to warm the bimetallic spring. As the bimetallic spring becomes warm, it releases its tension on the choke shaft and allows the choke plate to be gradually opened.

Although this general arrangement has been accepted commercially, certain inherent characteristics thereof have been found to cause undesirable results. Some of these results are improper choke come-off and come-on times. By come-off time is meant the time required to fully open the choke after the cold engine is started. By come-on time is meant that time required to close the choke after a substantially warmed engine is shut down. When the latter time is too short, there is a resultant difficulty in starting an engine after it has been shut down for a short time interval.

Since perfect coordination between come-off and come-on times is difficult to achieve, quite often a low temperature rate bimetallic spring is used, with the intent to produce the best come-off time available, regardless of the corresponding come-n time. However, when the spring used has a low enough temperature rate for proper choke operation in the earlier stages, the choke is apt to not come-off properly in the latter stages.

Accordingly, a general object of the invention is to provide means forming a part of the heat passage extending from the so-called stove in the exhaust manifold to the choke housing for controlling the choke come-off and the following description and accompanying illustrations wherein:

FIGURE 1 is a side elevational view, with portions thereof cut away, illustrating generally a carburetor embodying the invention, the carburetor being mounted on the intake manifold of an engine;

FIGURE 2 is an enlarged fragmentary view of the automatic choke housing taken on the plane of line 2-2 of FIGURE 1 and looking in the direction of the arrows;

FIGURE 3 is an enlarged, fragmentary side elevational viewof the invention taken on the plane of line 3-3 of FIGURE 1 and looking in the direction of the arrows;

FIGURE 4 is a cross-sectional view taken on the plane of line 4-4 of FIGURE 3 and looking in the direction of the arrows;

FIGURE 5 is similar to FIGURE 4, except that it is an elevational view, with a portion thereof broken away, to illustrate the invention under different operational conditions;

FIGURE 6 is an end view taken on the plane of line 6-6 of FIGURE 4 and looking in the direction of the arrows;

FIGURE 7 is a diagram illustrating the various bimetallic thermostat spring positions relative to the temperature rate of the spring;

FIGURE 8 is a graph comparing the operation of a choke mechanism embodying the invention with that of presently used choke mechanisms embodying various temperature rate bimetallic thermostat springs.

Referring to the drawings in greater detail, FIGURE 1 illustrates generally a carburetor 10 having a throttle valve 12 and an air intake 14 with induction passages therethrough and adapted to be controlled by a choke valve 16. The choke valve 16 is operatively connected to a bimetallic thermostat spring 18 (FIGURE 2) positioned in the automatic choke housing 20 by any conventional means, such as that shown in Patent No. 2,998,233 to Frederick J. Marsee. The carburetor is shown mounted on the intake manifold 22 near the usual exhaust crossover passageway 24.

An Inconel or other suitable heat tube 26 (usually referred to as the stove) leads through the exhaust crossover passageway 24 located within the intake manifold 22 and connects at the outlet 28 with a hot air tube 30 leading to the choke housing 20 and thence back again to the intake manifold 22 via the return line 32. The choke stove heat regulator valve 34 contemplated by the invention is incorporated in the heat tube line 30 in the proximity of the exhaust passageway outlet 28. Clean air enters the system through the cold air intake 36 of the cold air tube 38, usually located in the air intake 14 of the carburetor 10, and leads to the inlet 40 at the intake manifold 22.

FIGURE 2 illustrates the bimetallic thermostat spring 18 in contact with the projection 42 of the choke lever 44.

FIGURES 3 and 4 illustrate the choke stove heat regulator valve 34 as comprising a main body 46 suitably secured to the outlet 28, preferably by being slip fitted into outlet 28 by means of an extended small diameter end 48. The downstream end of the valve body 46 may be counterbored to a suitable depth so as to receive the heat tube 30. A formed bimetallic strip 50 is attached to a side of the valve body 46 by any suitable means such as rivets 52 and a hold-down plate 54. Located through a hole 56 at the free end of the bimetallic strip 50 is a loosely fitting closure element 58 having an enlarged flat end 60 facing the valve body 46 and an annular groove 62 near the small end on the opposite side of the bimetallic strip 50. The element 58 is held in place by a retaining ring 64 fastened around the annular groove 62.

FIGURE 4 further illustrates the fresh air bleed 66 connecting the axial passageway 68 with the outside Wall of the valve body 46. The bimetallic strip 50 and element 58 are designed such that the larger fiat face 60 of the element 58 is positioned away from the air bleed 66 so long as the bimetallic strip 50 is at its normal cold start condition.

FIGURE 5 shows the closure element 58 in a closed position, as would be the case when the bimetallic strip 50 has been heated by conduction through the valve body 46. The fit of the element 58 in the bimetallic strip 51 can be seen to be such as to permit radial and axial movement so that proper closing off of the air bleed 66 is accomplished.

:FIGURE 6 is illustrative of a suitable and economical hexagonal shape for the valve body $6. It can be readily seen that any external shape would be generally suitable, so long as there is a flat surface on the body 46 at tion and convection.

of a choke system embodying the invention. ample, a typical low temperature rate spring 18, rep

3 the outlet end of. the air bleed 66 and so long as the material and 'mass of the :body 46 is selected for proper conductive characteristics.

Operation Assuming, for purposes of illustration, that the engine As such, its. outer free end, would A typical high temperature rate spring 18, illustrated by B in' the figures would be such' that the choke valve 16 again would open-as spring B passed the point A location, and then continue travelling to a location as shown. FIGURE 8 indicates that the choke open location. would have beenreached relatively quickly. Incidentally, the choke valve 16, being fully open, would prevent the associated chokelever 44' and the projection 42 from passing beyond the point A; however, the free outer end of spring'18 could continue to wind up to point B. 1 i Y I If some intermediatetemperature rate'spring 18 were selected, there would-result a curve as illustrated by C in FIGURE 8. V a

It is apparent-in each instance, that 'a linear relationship exists between the time involved and the travel of the bimetallic thermostat spring '18. The eifect of this relationfold 2.2;will be drawn in the well known manner through the outlet 28 and thence through the heat regulator valve 34 and hot air tube 3t} into the choke housing 20. This air, of course, warms the bimetallic thermostat spring 18, causing it to wind up about its center and allowing the hoke valve 16 topr'ogre'ss toward a fully open fposition.

As'was mentioned earlier, the miss-0n time, when is that time required to fully open "the choke after the 'cold engine is started, cannot always be properly 'coordinated. Where a high temperature ,rate. bimetallic 'spring 18 has been selected'as most suitable in View of all the circumstances, the early rise in teinpeiature of the early movement of the spring may be ideal, but the come-oil time is very apt to be much too late. 'It is deficiencies such as these which are readily corrected by the invention. .Instead of the air passing through the heat tube 30 to the choke housing'Zt) in a normally heated condition during the first stages'of engine operation, lower temperature ambient air is caused to enter through the air bleed 66 to mix with .the heated air passingfthrough the axial passageway 68 of "heat regulator valve 34. This, of course, cools the air entering the choke housing 20, thereby influencing the bimetallic thermostat spring 18. to a lesser degree than would normally be the case. As the engine heats up and the exhaust passageway 24 through the intake manifold 22 becomes progressively hotter, the heat therefrom is transmitted to the body 46 of the regulator valve 34. As the mass of the valve'body 46 increases in temperature, the bimetallic strip 50 which is fastened thereto is also caused to heat up." As this bimetallic strip 50 increases in. temperature, it bends toward the fresh air bleed 66 in the valve'body 46., This causes the closure element 58 to be pressed against the flat surface surrounding the fresh air bleed 66, thereby regularly heated condition, causing the bimetallic thermostat spring 18 to complete its winding process, thereby permitting full opening of the choke valve 16.

The valve body 46 is heated to some extent by radia-. However, in the range of engine operation during which the regulator 34 must operate, heating by conduction from the exhaust manifold is an important additional source of heat.

Consideration of the diagram of FIGURE 7 and the curves of FIGURE 8 will illustrate specific advantages For exresented by A in the figures, would wind about its center to a position'approximately' as shown 'in FIGURE relatively long.

ship, when the invention is included in a system, is as illusstrated by the broken line curve. It can readily be seen that the initial winding of the thermostatic spring 18 can be retarded'in anydesiredmanner, as along O D, after 'whi'ch'ethe choke valve 16, can be quickly moved to a 'fully open position as represented by DeE This incorporates the best characteristics of both the low' temperature rate and the high temperature 'r-ate springs, in addition to permitting as slow a come-on time as desired without affecting the come-on time. In other words, 'the come-on time would remain the same as if the invention were not being used, and it would depend upon the normal rate of thcspringselected. For instance,

spring B of FIGURE 7 would still have tounwind from'B to 0 during the cooling off period of theengine before the choke plate would close.

The stove 26, the hot air tube 30 and the automatic choke housing 2i) are always present in some form or other on automatic choke carburetor installation-s. It is thus apparent that the control valve 34 'canreadily be "designed and constructed inanianner so that it can be sold as an aftermarket itemfor quick and easy installation on automatic choke systems not *originally'provided wi-thlthe invention, or as a replacement item. The valve -automatic means for operatinglsaid choke valve, said automatic means includinga housing, a thermostatic spring posltioned insaid housing, a conduit for communica-ting heated air from said stove to said housing, and

thermostatic means in said c-ondui-t for reducing the tem- -perature'of saidheated air prior to its entry into said housing.

'2. In an internal combustion engine including. an automatic choke type carburetor in which the choke position is controlled at least in part by a thermostatic element, -a housing in said carburetor for said'thermostatic element, a conduit communicating heated air from said engine to said housing, thermostatic means heated by said engine for reducing the temperature of'said heated air during'initial stages ofv engine operation prior to the entry of said air into said housing containing said thermostatic element. 1

' 3. In an internal-combustion engine including an intake manifold having a stove therein and a carburetor having an induction passage and a choke valve therein, a thermostatic element operatively connected to said choke valve for regulating the opcningand closing of said choke valve a) in accordance with engine temperature and a conduit for communicating heated air from said stove to said thermostatic element, a heat regulating means comprising:

(a) a body adapted to be inserted in said conduit and having an axial passageway therethrough,

(b) an air bleed leading from said axial passageway to the outside surface of said body, and

(c) a thermostatic means for at times closing off said air bleed at said outside surface of said body.

4. In an internal combustion engine including an intake manifold having a stove therein and a carburetor having an induction passage and a choke valve therein, a thermostatic element operatively connected to said choke valve for regulating the opening and closing of said choke valve in accordance with engine temperature and a conduit for communicating heated air from said stove to said thermostatic elernen-t, a heat regulating means comprising:

(a) a body inserted in said conduit in the proximity of said engine for being heated by conduction from said engine,

(b) an axial passageway through said body,

(c) an air bleed leading through the wall of said body from said axial passageway to the outside surface of said body, and

(d) a thermostatic means fastened to said body for closing off said air bleed in response to heat conducted through said body.

5. In an internal combustion engine including an intake manifold having a stove therein and a carburetor having an induction passage and a choke valve therein, a thermostatic element operatively connected to said choke valve for regulating the opening and closing of said choke valve in accordance with engine temperature and a conduit for communicating heated air from said stove to said thermostatic element, a heat regulating means comprising:

(a) a body having an axial passageway therethrough and adapted to be inserted in said conduit,

(b) an air bleed leading from said axial passageway to the outside surface of said body,

(c) a thermostatic element fastened at one end thereof to said body,

(d) a hole through the other end of said thermostatic element,

'(e) a valve member having an enlarged fiat face facing said air bleed and located in said hole of said other end of said thermostatic element, and

'(f) a retaining means for holding said valve member in said hole.

'6. In an internal combustion engine including an intake manifold having a stove therein and a carburetor having an induction passage and a choke valve therein, a thermostatic element operatively connected to said choke valve for regulating the opening and closing of said choke valve in accordance with engine temperature and a conduit for communicating heated air from said stove to said thermostatic element, a heat regulating means comprising: 9

(a) a body adapted to be inserted at the upstream end of said conduit,

(b) an axial passageway through said body,

(c) an air bleed leading from said axial passageway to the outer surface of said body near the upstream end thereof,

(d) a thermostatic element fastened at one end thereof to the downstream end of said body,

(e) a hole through the other end of said thermostatic element,

(f) a valve member having an enlarged flat face facing said air bleed and located in said hole of said other end of said thermostatic element, and

(g) a retaining means for holding said valve member in said hole.

'7. A heat regulating device for use in an internal combustion engine including an intake manifold having a stove and a carburetor having an induction passage and a choke valve, a thermostatic element operat-ively connected to said choke valve for regulating the opening and closing of said choke valve in accordance with engine temperature and a conduit for communicating heated air from said stove to said thermostatic element, said heat regulating device comprising:

(a) a body having a passageway extending therethrough so as to adapt the same to be inserted in said conduit,

(b) an air bleed leading from said passageway to the outside surface of said body, and

(c) thermostatic means for at times closing off said air bleed.

References Cited by the Examiner UNITED STATES PATENTS 2,840,065 6/58 Brown 1231 19 2,942,596 6/60 Carlson 123-119 2,986,380 5/61 Road 261-39 2,989,293 6/ 61 M-arsee 26139 2,996,057 8/61 Raymond 26139 2,998,233 8/61 Marsee 261-39 3,016,889 1/62 Sweeney 26139 3,058,727 10/62 Lucas 261--39 RICHARD B. WILKINSON, Primary Examiner.

HERBERT L. MARTIN, KARL J. ALBRECHT,

Examiners. 

